Following this how-to, you will be on your own.
Gentoo officially drop phonon-xine from the portage's tree, this means that Gentoo definitely does not support this method.
This solution is necessarily a dead end as there will certainly be a day when phonon-xine becomes definitely incompatible with phonon.
Let's just expect that when this time comes, the other backends will have reached an equivalent level of reliability and functionality.

I suggest you immediately read III.1.4 warning which mentions the most severe constraint impacting this howto before deciding to proceed.

I tested this successfully under amd64 stable arch and kde 4.7.4 and 4.8.3.

[EDIT : 2012.SEP.05 : Works also with 4.8.5]

Ultimate warning : No Gentoo Dev will tell you that it is sensible to follow this howto !

II PURPOSE

This howto is written for those who are not happy with the two existing phonon backends : phonon-vlc and phonon-gstreamer, whatever their reasons
(I personally get half a dozen that can be found using the search facility of this forum ) and who would look for a phonon backend that would be :
- Jack-aware
- Capable of reliably selecting the output sound device when more than a single hardware device available
- Capable of High and reliable quality resampling
etc...

- This should among other things download the necessary tarball.
- If it fails downloading the necessary tarball then refer to http://lfs.traduc.org/view/blfs-24012011/kde4/phonon-backend-xine.html, fetch the tarball from the link mentioned as well as the MD5 info and copy the file downloaded in your portage distfiles directory as phonon-backend-xine-4.4.4.tar.bz2
Then re repoman manifest

4/ media-libs/xine-lib

WARNING : last xine-lib stable under Gentoo-Portage to date is 1.2.1-r1
Because it was arbitrarily declared insufficiently tested, phonon-backend devs decided to prevent the build of phonon-xine with xine-lib-1.2
So phonon-xine is, as is, only buildable with xine-lib < 1.2
Of course it is possible to bypass this block but this would require patching some files in the phonon-xine tarball which goes beyond the purpose of this howto.
So, you should :

a/ Check if you get installed on your system some packages depending on xine-lib

Code:

# equery depends xine-lib

Then if the result is not empty, wonder whether these packages actually need a >= 1.2 xine-lib
Only if you are happy with a xine-lib < 1.2 then proceed to b/.

- This should among other things download the necessary tarball.
- If it fails downloading the necessary tarball then refer to http://lfs.traduc.org/view/blfs-24012011/multimedia/xine-lib.html, fetch the tarball from the link mentioned as well as the MD5 info and copy the file downloaded in your portage distfiles directory as xine-lib-1.1.20.tar.xz
Then re repoman manifest

5/ If you did all this work under root, change the owner/group of all the files you created :

Of course you want to set the xine useflag for the phonon and the phonon-kde packages... what else would we be doing here ?
Do this according to your preferred method, mine is to update my /etc/portage/package.use with the following lines :

Remember the result of III.4.a : If you had other packages depending on xine-lib then of course, you'll need to

Code:

# revdep-rebuild

4/ rebuilding the rest :

Code:

# emerge phonon-xine
# emerge phonon
# emerge phonon-kde

OK, that's it you should get the possibility to select the xine backend under kde's systemsettings/multimedia/phonon/backend tab.
Do not forget that after setting a new backend, KDE requires you logoff and login again before selecting your device preferences.

This works reliably for me, but I may have done errors when writing this howto.
Please cross-check twice and feel free to correct my post._________________

Last edited by aCOSwt on Mon Sep 17, 2012 8:06 pm; edited 7 times in total